package com.lagou.sqlSession;

import com.lagou.config.BoundSql;
import com.lagou.pojo.Configuration;
import com.lagou.pojo.MappedStatement;
import com.lagou.utils.GenericTokenParser;
import com.lagou.utils.ParameterMapping;
import com.lagou.utils.ParameterMappingTokenHandler;

import javax.sql.DataSource;
import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

public class SimpleExecutor implements Executor{
    @Override
    public <E> List<E> query(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        Connection connection = configuration.getDataSource().getConnection();

        String sql = mappedStatement.getSql();

        BoundSql boundSql = getBoundSql(sql);

        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();

        String paramterType = mappedStatement.getParamterType();

        Class<?> paramterTypeClass = getClassType(paramterType);

        for (int i=0;i<parameterMappingList.size();i++) {
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();

            Field declaredField = paramterTypeClass.getDeclaredField(content);
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);
            preparedStatement.setObject(i+1,o);
        }


        ResultSet resultSet = preparedStatement.executeQuery();

        String resultType = mappedStatement.getResultType();

        Class<?> resultTypeClass = getClassType(resultType);

        ArrayList<Object> objects = new ArrayList<>();

        while (resultSet.next()){
            Object o = resultTypeClass.newInstance();
            ResultSetMetaData metaData = resultSet.getMetaData();
            for(int i=1;i<=metaData.getColumnCount();i++){
                String columnName = metaData.getColumnName(i);
                Object object = resultSet.getObject(columnName);
                PropertyDescriptor propertyDescriptor = new PropertyDescriptor(columnName,resultTypeClass);
                Method writeMethod = propertyDescriptor.getWriteMethod();
                writeMethod.invoke(o,object);
            }
            objects.add(o);
        }

        return (List<E>) objects;
    }

    @Override
    public int executeUpdate(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        Connection connection = configuration.getDataSource().getConnection();

        String sql = mappedStatement.getSql();

        BoundSql boundSql = getBoundSql(sql);

        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

        List<ParameterMapping> parameterMappingList = boundSql.getParameterMappingList();

        String paramterType = mappedStatement.getParamterType();

        Class<?> paramterTypeClass = getClassType(paramterType);

        for (int i=0;i<parameterMappingList.size();i++) {
            ParameterMapping parameterMapping = parameterMappingList.get(i);
            String content = parameterMapping.getContent();

            Field declaredField = paramterTypeClass.getDeclaredField(content);
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);
            preparedStatement.setObject(i+1,o);
        }
        int updateRows = preparedStatement.executeUpdate();
        return updateRows;
    }

    private Class<?> getClassType(String paramterType) throws ClassNotFoundException {

        if (paramterType != null){
            Class<?> aClass = Class.forName(paramterType);
            return aClass;
        }
        return null;
    }

    private BoundSql getBoundSql(String sql) {
        ParameterMappingTokenHandler parameterMappingTokenHandler = new ParameterMappingTokenHandler();
        GenericTokenParser genericTokenParser = new GenericTokenParser("#{","}",parameterMappingTokenHandler);
        String sqlText = genericTokenParser.parse(sql);
        List<ParameterMapping> parameterMappings = parameterMappingTokenHandler.getParameterMappings();
        BoundSql boundSql = new BoundSql(sqlText,parameterMappings);
        return boundSql;
    }
}
